All I can offer is a suggestion and the usuals.
Suggestion, sign out of Google on the phone then unsync the phone.
1] If you click this link, http://www.google.com do you get Google's landing page? If so, can you use that to search? If not tell us details.
2] If 1 above fails, return to that landing page and see if you can sign out. If not, sign in then sign out.
3] Use another browser to sign out.
4] again if 1 above fails, start scanning for malware. Use your anti-virus scanner, then download, install, update and run separate scans with both the free versions of Malwarebytes Anti-malware and SUPERAntiSpyware.
See if any of those help.